ENGINES, BLOWING. No important improvement in type of blowing-engines used at blast-furnaces has been brought into use in this country in recent years, it having been generally considered that as the fuel used to drive these engines was the furnace-gas which would otherwise go to waste, attempts to economize this fuel were unnecessary. The com bining of blast-furnaces with steel-works, however, by which arrangement surplus fuel-gas at the blast-furnace may be used to drive the rolling-mills and other machinery, is likely to lead ere long to the adoption in blowing-engines of those principles which have contributed to the economy of steam in other engines, such as compounding, the balancing of strains through the multiple cranks, instead of equalizing them m enormous ffy-wheels, and increasing the speed of rotation. Two cylinder compound blowing-engines with cranks at 90° have already been built in England, but three cylinders with cranks at 120° would probably be a better arrangement. Much attention has been given to improvements of the air-valves of blowing engines for blast-furnaces, in order to diminish the air leakage and the resistance to the flow of air through the valve passages, and at the same time to increase the rapidity of the action of the valves, so as to allow greater piston-speed of the engine. These improvetnents have generally taken the form of an increase in the number and a decrease in the size of the valves. The Weimer Machine Works, of Lebanon, Pa.., builds blowing•engines with valves which are simply rectangular pieces of leather, about 7 by 2 in., stiffened by a metal plate. Each valve covers an opening of a slightly smaller size in a vertical iron grating forming the valve-seat, and is free to move to and from this grating at each reversal of the movement of the piston.
Positive valves operated by links attached to some moving part of the engine have been introduced to a limited extent, but their• merits have not yet been proved. The vertical type of engine is now generally used for blast-furnaces. horizontal engines, however, are still in use fro• blowing Bessemer converters.
Reynolds's Doable Vertical Blowing-Engine.—Fig, 1 represents a style of blowing-engine recently introduced by the E. I'. Allis Co., of Milwaukee. The chief feature of novelty of these engines lies in the construction of the frame. They are a pair of wrought-iron frame vertical engines with an air cylinder placed over each steam-cylinder ; the air-piston of each air-cylin (lei- is actuated by a piston-rod, which is attached to the steam-piston directly underneath. The Reynolds-Corliss valve-gear is used on both steam-cylinders: the air-cylinders being furnished with air-valves, conveniently arranged in chambers which are cast on each end of the cylinder and extend completely around it. The method of securing the valves in these chambers renders each one accessible and exposed to view when the engines are running. Any one of them can be removed and replaced by a new one at any time without dismounting the engine or disturbing any other valve. The first pair of this type of blowing-engine was placed in the Bessemer department of the Joliet Steel Works, Joliet, III.. in 1881.
See Ant-ComintEssoas. 111.AsT-Prux.Arr, IlLowEits, and SvovEs. lloT-BLAsT.